Control and locking of pivoting needle for pneumatic pipe carriers

ABSTRACT

The invention relates to a pivoting switch control mechanism for pneumatic conveyors. Transmission of the pivoting movement of the control arm (20) at its fulcrum on the movable switch (5) is effected by means of a return arm (21), articulated both on the control arm and on a stationary switch drive stop (26) which plays the role of fulcrum, said return arm further supporting a guide wheel (22) intended to follow the two inclined sides DC-CE of a single cam 24 mounted stationary upon a housing (1). The sealed switch installations are capable of operating for any direction of travel of the cartridges, by vacuum or pressure.

The invention concerns a system for control and locking of the pivotingswitch of a pneumatic tube conveyor unit.

In a pneumatic tube conveyor, it is known that there exist a certainnumber of sending-receiving stations served by one or more lines, oftenconnected to an automatic control center. In order to limit the cost ofthese installations, it is more and more common to use, to the extentpossible, a single conveyor line to which are here and there connectedshunt lines leading to a station. At the connection point, it istherefore necessary to have a switching mechanism which is in continuoussealed connection with the line sections it joins.

A sealed housing surrounds the tube inlets, inside of which are locatedthe switching mechanisms themselves. However, there must also be a sealat least between the pivoting end of the switch and one of the lines.

Various mechanisms exist for carrying out the pivoting of the switch andits sealed locking against the end of a line, consisting of giving saidswitch, in addition to its lateral pivoting movement, an axialdisplacement permitting it to compress, at the end of its travel, anannular gasket mounted on the line so as to complete the seal, saidaxial displacement being made possible by a flexible coupling playingthe role of pivot axis.

Compression of this gasket by the pivoting tube requires applicationonto the switch of a certain axial force and, consequently, a sturdymechanism having a relatively high-powered control unit. Furthermore, inknown systems, the system cannot be operated in all positions, due tothe variable force of gravity on the movable switch according to theorientation of the switch assembly.

In order to improve the systems for controlling and locking pivotingswitches, while at the same time eliminating the difficulties inherentin known constructions, the applicant has developed a new control andlocking system which has the following advantages. First, the controlmechanism requires only a low power motor, since the angle of pivot atthe fulcrum of the control arm is small. Next, the system is able tooperate in any position, whether the switch is horizontal, vertical,directed upward, downward, etc., and for any direction of travel of thecartridge. In addition, construction is simple, inexpensive, and reducedin size, thus enabling easy incorporation into the switch housing.Finally, by virtue of its disposition inside a sealed housing, the newsystem of the invention operates without any need to seal the shuntline.

According to an essential characteristic of the invention, transmissionof the pivoting movement of the control arm, at its fulcrum on themovable switch, is effected by means of a return arm articulated both onthe control arm and on a switch drive stop which plays the role offulcrum, said return arm further having a guide wheel intended to trackthe two inclined sides of a single cam mounted stationary onto theframe.

According to one particular characteristic of the invention, there isprovided a pivoting paddle turning about the control axis and projectingup to the switch drive stop, intended to compensate for the weight ofthe mechanisms and the switch under certain conditions of use.

Other particular characteristics and advantages of the invention willemerge from the following description of one embodiment, with referenceto the attached drawings, which represent:

FIG. 1: a partial vertical cross-section of the pivoting switch and itscontrol mechanism;

FIG. 2: a cross-sectional view along line AA' of FIG. 1;

FIG. 3: a partial cross-sectional view along B of FIG. 1;

FIGS. 4 and 5: cross-sectional views analogous to FIG. 2, showing thepivoting switch in intermediate position and pivoted position;

FIG. 6: a partial vertical cross-section of the switch, according to onevariant.

The switch represented, particularly in FIGS. 1 and 2, is containedwithin a sealed housing 1 which, on one side, receives a connectionferrule 2 on the main line and, on the other, a connection ferrule 3 onthe opposite section of the main line, as well as another shunt ferrule4, connected, for example, to a transmitting and receiving station inthe network. Movable tube 5 of the switch is intended to connect ferrule2 to one or the other of ferrules 3 and 4 by pivoting about an axiswhich is perpendicular to the axis of the main line at the level offerrule 2. Articulation of the pivoting switch at the ferrule is sealedby a flexible coupling 6 fastened both to ferrule 2 and crown 7, whichis integral with switch 5. In addition, two diametrically opposed guidepins 8 provided on ferrule 2 penetrate into corresponding holes 9 ofcrown 7. They permit switch 5 to pivot within the plane of FIG. 2 andenable a certain axial displacement of switch 5 during its pitovingmotion, as will emerge further on.

On the side opposite ferrule 2, switch 5 moves in guides 10 fastened tohousing 1 and is equipped with a hollow sleeve 11, the projectingportion of which, having a truncated cross-section, is applied againstflexible annular gasket 12 mounted in a channel provided on the faceoriented toward the inside of the housing of connection ferrule 3 of themain line, as shown in FIG. 2. The lateral pivot of switch 5 is limitedby stationary stops 13 which are also integral with housing 1.

Control of the pivoting and locking of switch 5 is assured by anelectro-magnet 14 mounted above the housing. It can be seen in FIGS. 1and 3 that movable core 15 of electro-magnet 14 is attracted in thedirection of the arrow, causing lever 16 to pivot, against the returnforce of spring 17. Lever 16 is integral with an axis 18 which pivotswithin guide shaft 19 mounted on the housing, the end of which projectsinto sealed housing 1. To the lower end of the axis is welded a controlarm 20 which extends inside the housing above pivoting switch 5. Alongan axis 31, perpendicular to the control arm at its extremity, turns atriangular return arm 21 which also extends inside the housing above thepivoting switch. Said return arm 21, which is articulated at the end ofthe control arm, further carries a guide wheel 22 having a verticleaxis, mounted above the return arm on pivot 23. Said wheel 22 comes intolateral contact with a flat cam 24, fastened onto the inside of housing1 above the return arm. Cam 24 has two inclined sides CD-CE proceedingfrom a bending point C which is essentially disposed within the axis ofconnection of ferrules 2 and 3. Another guide gradient 25 is alsofastened to the inside of housing 1, parallel to side CE of cam 24, at adistance which is slightly greater than the diameter of wheel 22. Thetrack thus formed between gradient 25 and side CE of cam 24 serves toguide wheel 22 during the pivoting motion of switch 5. The opposite endof return arm 21 carries a stud 26 in openig 40 which engages within awork shaft 27 which is integral with shaft 5. Said stud 26 thusconstitutes the fulcrum on the movable switch of the pivot controlmechanism consisting of control arm 20 and return arm 21. According to anon-represented variant, the opposite end of return arm 21 is equippedwith a ring or opening into which is engaged a stud attached to switch5. In the two preceding cases, the switch-return arm connection iscompletely analogous.

Furthermore, a small vertical stop 32, attached under gradient 25,limits the lateral displacement of control arm 20. In addition, on axis18, above control arm 20, turns a pivoting paddle 28 which plays therole of counter-weight, one end 29 of which (the side of coupling 2)bears a weight 33, while the opposite end has a fork-shaped section 30which surrounds stud 26. It will be noted in FIG. 1 that said forkencloses stud 26 below return arm 21. The center part of paddle 28, asseen in FIG. 2, is largely hollowed-out so as not to impede the movementof axis 31, forming the articulation of return arm 21 on control arm 20.The paddle thus mounted pivots about axis 18, following the movement ofstud 26, and thus of switch 5, which drives said paddle by the edges offork 30.

The switch operates in the following manner. FIG. 2 shows switch 5 inso-called "rest" position, in which a sealed connection between the twoopposite sections of the main line is made. In this case, withelectro-magnet 14 not excited, the return force of spring 17 (FIG. 3) isexerted on the end of lever 16 so as to maintain axis 18 and control arm20 in the position of FIG. 2. With switch 5 applied against stop 13,control arm 20 is also applied against stop 32. Consequently, thefulcrum formed by stud 26 is aligned with control arm 20. The threealigned points: axis 18, axis 31, stud 26, represent the maximumpossible distance between axis 18 and stud 26, i.e., control arm 20 andreturn arm 21 exert a force on stud 26 in the direction of axialmaintenance of switch 5 in locked position, in which sleeve 11compresses annular gasket 12 and makes the seal between pivoting switch5 and ferrule 3. It will be noted that stud 26 blocked laterally sinceswitch 5 is in contact with stop 13 and control arm 20 is also blockedlaterally by stop 32. Wheel 22 thus occupies the position represented,in contact with side CD of cam 24.

When switch 5 has to pivot into alternate position facing ferrule 4, endsleeve 11 must first be disengaged axially from annular gasket 12, priorto the actual pivoting motion.

This initial step is illustrated in FIG. 4. Upon excitation ofelectro-magnet 14, the attraction of movable core 15 against the forceof spring 17 (FIG. 3) initiates the pivoting motion of axis 18 andcontrol arm 20 in the direction indicated by the arrow. In the pivotingmotion, axis 31 drives return arm 21, of which wheel 22 follows inclinedside DE of cam 24. Since stud 26 is therefore no longer aligned withcontrol arm 20 (broken line 18-31-26), it is necessarily closer to axis18. Consequently, when wheel 22 has essentially reached point C, returnarm 21, by pivoting, has induced the withdrawal of switch 5 by severalmillimeters in the direction of the articulation of switch 5, i.e., theend of the latter has cleared annular gasket 12 by an equal distance.The switch may then pivot. Paddle 28 follows the motion of stud 26thanks to fork 30, and its counterweight thus balances the moving massas indicated below.

The second pivot phase is illustrated in FIG. 5. Starting from theposition indicated above (wheel 22 at point C), the pivoting movement ofcontrol arm 20 continues. At the end of control arm 20, axis 31, onwhich turns return arm 21, effects a circular movement, as indicated.Wheel 22, on the other hand, is guided in the track defined by gradient25 and side CE of cam 24. The combination of the pivoting movement ofaxis 31 and the rectilinear displacement of wheel 22 assures thetranslation and simultaneous pivoting of return arm 21, which ismanifested in a displacement of stud 26, and therefore of switch 5,until the latter comes into contact with stop 13. The switch is nowpositioned facing ferrule 4 and is ready to effect the passage of acartridge coming from or going to a shunt line. Switch 5 is not yetsealed against ferrule 4 at this point. The passage of air betweenferrule 4 and the inside of the housing has no effect on the operationof the unit. This diverted position of the switch is called the workingposition, which corresponds to the excitation of the electro-magnet. Assoon as the latter is interrupted, the switch returns to its position byreverse motion under the force of spring 17, which causes the return ofcontrol arm 20 to stop 32. In the course of these displacements ofswitch 5, pivoting paddle 28, fork 30 of which is permanently engagedaround stud 26, follows the pivoting motion of the switch. It was seenthat its end 29 carried a counterweight 33. The function of the paddleis to compensate for the weight of the switch and its related controlmechanisms in all possible operating positions of the switch.

If the switch operates flat in the plane of FIG. 2, the horizontaldisplacement of switch 5 along guides 10 is accomplished withoutdifficulty by the electro-magnet or its return spring. Here pivotingpaddle 28 plays no role at all. If, on the other hand, the switchoperates in a vertical plane, neither the force of the electromagnet norof the return spring will be sufficient to displace the control arm,return arm and switch from a low position to a high position. Paddle 28and its counter-weight 33, which pivots about horizontal axis 18 andholds pivoting switch 5 by stud 26, equilibrates the moving masses ataxis 18. This complementary balancing system, joined with the switchcontrol and locking mechanisms, is extremely advantageous since itenables installation of the switch in any position, for any direction oftravel of the cartridge, whether moved by pressure or vacuum. Thepivoting switch is thus very flexible in use and lends itself to allinstallations.

FIG. 6 shows variants of the invention. A first represented variantconsists of disposing a rotary electromagnet 34 in place of the classicelectromagnet shown in FIGS. 1 and 3. This rotary magnet is placeddirectly on the housing and its axis 35 is substituted for axis 18 inthe other embodiments. Control arm 20 is keyed onto axis 35. This rotarymagnet possesses its own return spring. It thus eliminates the mountingof the pivoting lever (FIG. 3) and releated elements and therebyrepresents an interesting improvement from the point of view ofsimplification and cost. Since, by construction, the travel of controlarm 20 is short, a low-power rotary magnet having a short travel caneasily be adapted.

The second variant shown consists of mounting pivoting paddle 28 notabove the switch, i.e., on axis 18 of control arm 20, but on the otherside of switch 5. The paddle is here mounted on a pivot 36 fastened tothe inside of housing 1. On the side opposite counter-weight 33, itsfork-shaped end 30 encloses a stud 37 analogous to stud 26, fastened tothe lower part of the switch. The paddle balances the moving masses inthe same way. Its particular position on the side opposite themechanisms makes the manufacture of the switch easier, and enables morespace to be made available in the upper area for actual locking andcontrol mechanisms.

The invention is of course not limited to the preceding examples ofparticular example embodiments but rather encompasses all constructivevariants.

I claim:
 1. Switch for pneumatic tube conveyor comprising, within asealed housing, a pivoting switch joining one section of main line atthe side of its axis of pivot to a second section of main line or to asection of shunt line at the opposite side, said switch being sealedagainst a second section of main line by a slight axial displacement ofthe switch in the direction of compression of an annular gasket disposedat an end of said second section, and the transmission of motion betweena drive mechanism and a fulcrum integral with the pivoting switch beingcarried out by a pivoting control arm acting upon a substantiallytriangular return arm, one angle of which catches said fulcrum, thereturn arm (21) pivots about an axis (31) carried on the end of thecontrol arm (20), on which it turns along another of its angles and thusfollows totally the pivoting motion of said control arm, and that itcarries, in the area of its third angle, a guide wheel (22), appliedagainst at least one stationary cam (24) serving to orient said returnarm during the pivoting of the control arm.
 2. Switch according to claim1, the pivoting control arm (20) disposed inside the housing above thepivot plane of switch (5) is fastened to an axis of rotation (18)passing through the housing and worked by a driving electromagnet (14)having a short travel.
 3. Switch according to claim 2, the drivingelectromagnet is a rotary electromagnet, the axis of which is combinedwith axis (18) of control arm (20).
 4. Switch according to claim 1, thefulcrum of the return arm (21) on the pivoting switch (5) is a stud (26)fastened in proximity to another angle of the return arm and entering awork shaft (27) attached to the switch.
 5. Switch according to claim 1,the fulcrum of the return arm (21) on the pivoting switch (5) in anopening (40) provided in proximity to another angle of the return arm,into which penetrates a stud (26) attached to the switch.
 6. Switchaccording to claim 1, the wheel (22) is mounted on pivot (23) located inproximity to the third angle of the return arm (21), on a level distinctfrom that of said return arm.
 7. Switch according to claim 1, the cam(24) fastened to the inside of the switch housing (1) has a verticalsurface at the level of the wheel (22), having two inclined sides CD andCE proceeding from a bending point C which is substantially disposedwithin the axis of connection of the main line sections.
 8. Switchaccording to claim 7, a guide gradient (25) is also affixed to theinside of the housing (1) parallel to side CE of the cam (24) at adistance slightly greater than the diameter of the wheel (22).
 9. Switchaccording to claim 8, a stop (32) fastened onto the gradient (25) limitsthe lateral displacement of the control arm.
 10. Switch according toclaim 1, a counterweight device, intended to compensate for the weightof the drive mechanism and the switch under certain conditions ofinstallation of the switch, is mounted so as to pivot and is worked bythe switch.
 11. Switch according to claim 10, that the counterweightdevice consists of a pivoting paddle (28) supporting a weight (33),turning about the axis (18) of the control arm (20) and projecting up tothe switch drive stud (26).
 12. Switch according to claim 11, the end ofthe blade has a fork-shaped cross-section (30) in order to enclose thestud below the return arm (21).
 13. Switch according to claim 10, thecounterweight device consists of a pivoting paddle (28) supporting aweight (33), turning on a pivot (36) fastened to the inside of thehousing (1) and projecting up to a stud (37) integral with the switch.